topic Re: Remote DHCP for wireless lan in Wireless

Remote DHCP for wireless lan

absuizo14 — Mon, 05 Jul 2021 15:11:38 GMT

Hi Guys,

a client has an existing wlan setup where in the WLC is on a different location from the APs each having different routing domains now to establish communication between the 2 static routes are used and their next hops is located on a different routing domain. lets just say location 1 has core 1, location 2 has core 2 and location 3 has core 3.

core 1 has the following details:
vlan 1,500,600,20
WLC
next hop to get to core 3 is through core 2

core 2 has the following details:
no access

core 3 has the following details:
vlan 100,400
APs
next hop to get to core 1 is through core 2

right now wireless clients recieve ip address from vlan 500,600 and 20 but they have decided to replace their WLC and place it in core 3 with the APs. the problem is that dhcp server is core 1 and wireless clients still need to get ip addresses from vlans 500,600 and 20.

Re: Remote DHCP for wireless lan

Flavio Miranda — Wed, 31 Jan 2018 14:38:35 GMT

There are many ways to fix it. You can use, for example, "ip-helper address" on Core 3 pointing to Core 1.

-If I helped you somehow, please, rate it as useful.-

Re: Remote DHCP for wireless lan

absuizo14 — Wed, 31 Jan 2018 22:36:47 GMT

Hi
do i have to define the l2 vlan from core 1? where do i configure the "ip-helper address" command? for example:

core 1
!
interface Vlan1(management)
ip address 192.168.198.128 255.255.255.128
!
!
interface Vlan20(VIP)
ip address 192.168.198.128 255.255.255.128
!
!
interface Vlan500(DATA)
ip address 192.168.7.1 255.255.255.0
!
interface Vlan600(DATA2)
ip address 192.168.8.1 255.255.255.128
!

core 3
!
interface Vlan100(SW MANAGEMENT)
ip address 192.168.177.9 255.255.255.128
!
!
interface Vlan400(WIRELESS MANAGEMENT)
ip address 192.168.178.132 255.255.255.128
ip-helper address 192.168.7.1 <------------ place here?
!

if i were to configure vlan interface for vlans 20,500 and 600 on core 3 would that become a discontiguous network?

Re: Remote DHCP for wireless lan

Flavio Miranda — Wed, 31 Jan 2018 22:50:41 GMT

It is not necessary. The helper-address is created on the core where the WLC is connected. Then you point to the IP address of remote core.

It is not necessary to extend the vlans only DHCP scope.

What happen with helper-address is that, when a client request an IP address to the WLC and the WLC send the client dhcp request out to core via broadcast, the core will take the broadcast packet, encapsulate in a unicast packet end send out to the remote core via layer 3.

-If I helped you somehow, please, rate it as useful.-

Re: Remote DHCP for wireless lan

jkilleda — Fri, 02 Mar 2018 15:53:46 GMT

Hello Adorico,

Remote DHCP for wireless lan

Config dhcp on core 3 , add vlan 500,600,20 on core 3 , when you are adding WLC on core 3 you need to replicate the whole config from core 1 to core 3